1. Field of the Invention
The present invention relates to an electrophotographic copying machine including a developing unit using a toner as a developer and toner supply container therefor.
2. Description of the Prior Art
A personal or domestic small-sized copying machine which is used relatively infrequently is popularized. As a method of supplying a toner to a developing unit installed in such a copying machine, for example, generally a used toner cartridge is removed from the developing unit and replaced with a new toner cartridge, or the toner is replenished to the removed toner cartridge. In recent years, taking a serious view on simple maintenance, a detachable replacement type developing unit has been developed in which a one-way developing unit is used and replaced with a new developing unit when the toner has to be replenished
Now, when replacing the toner cartridge or replenishing only the toner, though it is advantageous in restraining the running cost, a problem is encountered in that the copying machine body, the developing unit or an operator's hands and clothes, and the like are stained with the toner scattered during operation.
Though it may be possible to increase the amount of toner to be charged to suppress the replenishing frequencies, the amount is limited due to enlargement of the machine size. Furthermore, in a two-component type developing unit, when only the toner is replenished for a long duration of use, the copying quality may be deteriorated due to wear and stain of a carrier.
In consideration of such circumstances, a system of restraining deterioration of the copying quality as well as avoiding stains due to the toner at replenishment by replacing the developing unit itself has been devised. However, in this system, since the entire developing unit has to be replaced when the toner is emptied, there is a problem that the cost for one copy or the copying cost is high.